Process of altering bicycle frame head tube angle by cutting a slot in bottom bracket and bending frame here

ABSTRACT

The recumbent bicycle design referred to here is the type which has the center of the crankset located vertically above the front wheel, and positioned horizontally anywhere from directly above the front wheel, to a position which is ahead of the front wheel, and is determined by the rider&#39;s leg length.  
     This type of recumbent bicycle generally has a small diameter front wheel, which reduces or eliminates interference between the front wheel and the rider&#39;s feet when steering the bike through turns when pedaling.  
     If one were to convert a standard diamond shaped bicycle frame for use as a recumbent bicycle by installing:  
     a) small diameter front wheel (or pair of small diameter wheels)  
     b) tube (boom) extending forward from the head tube and has a crankset positioned at the front,  
     then the bicycle would not steer properly. This patent offers a method of adjusting the angle of the head tube to improve steering.

BACKGROUND

[0001] 1. Field of Invention

[0002] This process allows for the adjustment of the head tube anglewithout removing the head tube from the bicycle frame.

[0003] 2. Description of Prior Art

[0004] Recumbent bicycles have rapidly been gaining popularity and arecurrently expensive. An inexpensive method of producing a recumbentbicycle is to weld a boom onto the front of a juvenile, or BMX bicycle.

[0005] The advantages here are that the bicycle has a low height, foreasy step-over, and a low seat height. Also, the small wheels(particularly the front wheel) allows for ample clearance between therider's feet/pedals, and the wheel. This is important to preventfoot/wheel intereference while pedaling the bicycle through turns.

[0006] The disadvantage of using the BMX or juvenile type bicycle isthat it has a short wheelbase, and produces a rough or choppy ridingrecumbent bicycle.

[0007] Another method of producing a recumbent bicycle would be to takea larger bicycle, with a longer wheelbase, and convert this type ofbicycle for use as a recumbent. In addition to having a longerwheelbase, this type of bicycle also have larger wheels. To convert thistype of bicycle for use as a recumbent, one must install a smallerdiameter front wheel, to eliminate the foot/wheel interference whenturning.

[0008] One may also choose to also install a smaller diameter rearwheel. Using either combination of wheels results in a bicycle whichdoes not steer properly. To improve steering, one must alter the headtube angle. This requires disconnecting the head tube from the frame andreattaching it at the desired angle.

[0009] NOTE: The head tube angle is the angle of a line (projectingthrough the ends of the head tube and is parallel to the head tube),which intersects with the ground. This angle is deterimined by viewingthe bicycle from the side. (FIG. 1, page 1, letter alpha)

OBJECTS AND ADVANTAGES

[0010] By using the method I have outlined, one:

[0011] a) does not need to disconnect the head tube from the frame;

[0012] b) eliminates time consuming process of reattaching head tube;

[0013] c) eliminates time consuming process of aligning head tube;

[0014] d) produces a rideable bicycle quickly and with less expense thanif one were to build from scratch.

OPERATION—FIGS. 1, 2, 3, 4

[0015] To convert a standard diamond frame bicycle for use as arecumbent bicycle with a small diameter front wheel, one must adjust thehead tube angle for improved steering geometry with the smaller diameterfront wheel.

[0016] NOTE: In certain applications (tall riders), it is possible toleave the top tube connected to the head tube, slightly reduce thelength of the seat tube, and reattach the chain stays, but mostapplications will require a lower top tube height.

[0017] To lower the height of the top tube, one must remove the toptube, reduce the length of the seat tube, install a new top tube, andreattach the chain stays. This is the method outlined below.

[0018] PLEASE REFER TO FIG. 1, PAGE 1, FOR A REFERENCE TO THE NAMES OFTHE COMPONENTS OF A BICYCLE FRAME.

[0019] (FIG. 2, Page 2) The first step is to make cuts in the frameat: 1) top tube, 2) chain stays, 3) seat tube, and 4) across the bottombracket shell between the down tube and chain stays.

[0020] (FIG. 3, Page 2) Bend the frame to increase the width of theslot, which was cut across the bottom bracket shell, to achieve thedesired head tube angle.

[0021] NOTE: THE FOLLOWING STEPS ARE NOT SPECIFICALLY COVERED IN THISAPPLICATION, BUT ARE LISTED TO ILLUSTRATE THAT THIS METHOD PRODUCES ACOMPLETE AND RIDEABLE BICYCLE.

[0022] (FIG. 4, Page 3) The top tube (#2, shaded) is welded to the seattube and head tube.

[0023] The seat stays (#1, and outlined) are bent forward and welded tothe top tube.

[0024] The slot in the bottom bracket shell is welded, or is bridged andwelded, (#3).

[0025] The boom assembly is welded to the head tube.

[0026] The seat, fork, front wheel, rear wheel, handlebar, riser andstem are installed.

SUMMARY

[0027] By using this method, one may rapidly produce rideable recumbentbicycles cheaply, using a previously produced bicycle. By eliminatingthe need to remove the head tube from the frame, one eliminates the timeconsuming process of reattaching and realigning the head tube to theremaining frame.

[0028] Also, the weld integrity of the original frame is not compromisedat the head tube to down tube joint, as it is not disturbed.

1. I claim a process for converting a diamond shaped bicycle frame foruse as a recumbent bicycle frame which: a) allows for the use of asmaller diameter front, or combination of smaller diameter front/rearwheels b) allows for the head tube and down tube to remain connected tothe frame c) disconnects the top tube from either the head tube, seattube, or both d) allows for the adjustment of the head tube angle forimproved steering geometry with said smaller diameter front wheel, orcombination of smaller diameter wheels e) produces a slot across thebottom bracket shell located between the down tube and chain stays f)said adjustment of head tube angle occurs by bending the frame at thebottom bracket shell to either increase or decrease the width of saidslot